1 Litre of Tears. I don't think there was one episode that didn't make me cry. 
Thriller Dramas:
Two Weeks
Remember – War of the Son (2015) -last episode is the best ending of a drama I have seen)
White Christmas (2011)

Melodramas:
1 Litre of Tears (2005)
Secret (2013)
Ugly Alert (2013) - Early Episodes were real tearjerkers for me.
Thank You (2007)
Mask (2015)

Historical Dramas :
Empress Ki & Six Flying Dragon (Masterpieces of acting and everything else)
(many re-watches and still it manage to feel their sad soul, which makes me liking them more)
The Moon Embracing the Sun
It's the only time I had to pause the drama because I was crying so hard I couldn't read the subtitles. I didn't even really like this drama all that much, but a certain characters choices left me completely heartbroken.
Who Are You: School 2015 - I liked the drama from the beginning and the later episodes in the drama just made me cry so much, mostly because I'm so weak with goodbyes. anD THE ENDING I WAS CRYING FOR HOURS AFTER THE LAST EPISODE HAD ENDED the ending didn't do anything good for my health. But the drama was so good. But the ending literally stepped on my heart.
Page Turner - I totally fell in love with Kim So Hyuns and her acting from the drama above, School 2015, so I decided to watch this drama too, since she plays the main role. And her acting. Wow. I literally cried my eyes out, especially in ep. 1. But somehow the drama got me to laugh while crying, somehow. It was so sad but still funny at the same time? And it just made the drama a masterpiece in my eyes. It was so good. I recommend it so much.
To The Beautiful You - I literally cried so much to this drama and it's something that my friend(that also likes k-dramas and has seen this drama) questions a lot, since she never ever found herself even shed a tear to this drama(?!) But, as said, I'm so ridiculously weak with goodbyes. And this drama literally threw knives in my stomach the last episodes.
It's Okay, That's Love - At first, I was too chocked to even react. I literally sat with my jaw that had dropped to the floor. And then I reacted. Just n-no. It hurt me so much. It hurts so much to even think about. I'm not okay. But the drama was a masterpiece, so it so was worth it. But still. My heart. Aoch.
1 Litre of Tears TT_TT 
I can't believe that I watched Koizora (drama) after that ...

since 2009 I never touched a japanese (disease) drama again 
Sorted by crying intensity:

6. Reply 1988 (more of a bittersweet cry than an ugly cry)
5. Incomplete Life
4. Who Are You (2013) (not because it was amazing...but because of what happened to one specific character)
3. King2Hearts
2. The Bridal Mask
1. Battle of Changsha (I don't think it's possible to watch this and not get emotional)
Hm, many dramas have made me cry but ill name a few:

Secret (Korean drama) - Absolutely heartwrenching drama. Gives you a very wide range of emotions in each episode. Hwang Jung Eum acting was superb. I didn't mind her crying in every episode because it was always on point.

Kono yo No Hate (old japanese drama) - Dark romances always have big impact on me.

Tree of Heaven (Korean drama) - The very first asian drama i ever watched. Prepare your tissues.




1 Litre of Tears - While I've watched this drama I always had the urge to cry. After I've watched this drama I treasured my health much more.
Empress Ki - Sometimes I couldn't stop crying. It's bittersweet and makes you feel a million emotions.

There are a lot of dramas that made me cry but these ones were the most touching for me :'(
Loving You A Thousand Times.. I really cried buckets of tears..
Yi San 
Dong Yi
The Moon Embracing The Sun
The Princess Man


Yi San is definitely ranked number 1 when it comes to making me cry. I cried twice in this drama, once in the middle and then again due to a specific scene in the last few episodes. After watching that scene at the end and then completing the drama, I had felt like my life was so out of place and that for a moment I wondered if I'd be able to just carry on with my daily life. It was then that I realised just how emotionally involved I had become with this drama. After watching over 70 episodes, I had become so used to the characters that it almost felt like I knew them personally, and so after the sad scene at the end, it broke me and the dam, thus leading to a waterfall of tears that lasted for DAYS. I thought I could sleep on it and recover but nope. The next day I had gone to rewatch the scene and ended up bursting into tears again. Why had I rewatched the scene? Because it was all I could think of and honestly I had exams the next week and needed to get a grip. Though eventually, after a week I had recovered, a few months later I decided to rewatch an episode at the end, and I think you can guess what happened. Yep. I cried. Again. Yi San does have its boring scenes, but after completing the drama, I don't think I'll ever quite fully get over it. 

As for Dong Yi, The Moon Embracing The Sun, and The Princess' man, I haven't got any melodramatic story to tell. All I can say is that they did make me cry a lot. But I quickly got over them. In the case of The Moon Embracing the Sun though, I give all the credit for my tears to Kim Yoo Jung's phenomenal acting. She brought her character to life and made me really share her emotions like they were my own. She was much younger then, and was the best child actress. I expect a lot of great roles from her in the future. 
1 liter of tears (this will definitely make you cry and more than 1 liter!)
Signal
I'm sorry I love you
Crying out Love, in the Center of the World
Also add:


Marriage contract
1 Liter Tears almost every episode.
Memories From Bali, I'm Sorry I Love You,
The most recent that made me cry was Scarlet Heart - for the last 2 eps only tears came out.
 I've seen LOTS of melos, but I'm sorry I love you takes the cake